All four were taken to hospitals in the Italian port of Livorno after the crew of the MSC Orchestra reported the illnesses, the ministry said. More than 2,800 doses of the antibiotics ciprofloxacin and rifampicin were issued for passengers, and the ministry said passengers who have disembarked in the past week should take similar precautions.

The 294-meter (965-foot), 2,500-passenger Orchestra is currently in the French port of Villefranche sur Mer, on the outskirts of Nice, and the ministry said Italian authorities have notified their French counterparts. MSC, the passenger arm of Italy's Mediterranean Shipping Company, said it was doing "everything necessary to safeguard the health of its guests and all the crew members."